Wear-resistant reinforcing coating applied to a particulate substrate

ABSTRACT

A method of forming a wear-resistant reinforcing coating on a substrate, such as concrete, wood, metal or particulate. A reinforcing fiber mat is placed on the substrate and a liquid matrix material is mixed with small colored stones. The mixture of matrix material and stones is poured onto the mat, and the liquid wets the mat and contacts the substrate. After curing, a composite coating is formed with stones as the wearing surface. A membrane can be interposed between the substrate and the reinforcing coating to prevent adhesion and “starving” of the mat.

This application is a divisional of U.S. application Ser. No. 10/039,783filed Nov. 9, 2001 now U.S. Pat. No. 6,716,482.

(E) BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to a composite coating that reinforcesand provides wear-resistance to flooring, sidewalks, driveways and othersurfaces.

2. Description of the Related Art

Conventional floors, sidewalks, driveways and other foot, bicycle andautomobile traffic-bearing surfaces are commonly made of concrete,asphalt pavement, wood, fiberglass and metal. All of these flooringmaterials have problems due to poor strength, wear-resistance orrot-resistance. For example, concrete is very wear-resistant, but itcracks due to soil settling beneath it and it can become unattractivedue to spalling on the top surface. Asphalt pavement wears well, but italso cracks as the asphalt between the aggregate is worn away by rain.Wood decking is strong and flexible, but it rots and discolors as itweathers. Fiberglass is strong and flexible, but it tends to be slipperywhen it is wet, as is metal, which can also rust.

The prior art attempts to address problems with concrete by coating itwith hardening liquids, and in some instances, forming composites thatbond to the concrete. Asphalt is repaired in the prior art by forming acomposite on a layer of asphalt prior to applying a new layer ofasphalt, thereby preventing “reflective cracking” caused by theweakening of the new layer of asphalt directly above the old crack.

All of the prior art methods of repairing the underlying floors,driveways or sidewalks either fail to repair the underlying structureproperly, or fail to provide a surface that is suitable for the trafficthat will be borne by the final product. Furthermore, some repairscannot be removed from the underlying substrate for remodeling, forexample. Therefore, the need exists for a coating, and a method foreasily constructing the same, that is strong, flexible andwear-resistant.

(f) BRIEF SUMMARY OF THE INVENTION

The present invention relates to a wear-resistant reinforcing coatingformed on virtually any existing substrate surface over which traffic,including pedestrian, bicycle and automotive, passes. Such substratesinclude sidewalks, stairs, driveways, roads, floors, boat decks, bridgedecks, porches and wooden decks. Furthermore, the invention can be usedon other surfaces, such as table tops, kitchen counter tops and anyother surface that needs to be wear-resistant and strong.

(G) BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a diagram illustrating the steps in a preferred method.

FIG. 2 is a side view in section illustrating a coating formed on aparticulate base.

FIG. 3 is a side view in section illustrating a coating formed on awooden base.

FIG. 4 is a diagram illustrating the steps in an alternative method.

FIG. 5 is a diagram illustrating the steps in an alternative method.

FIG. 6 is a diagram illustrating the steps in an alternative method.

FIG. 7 is a side view in section illustrating a solid substrate coatedwith the preferred wear-resistant reinforcing coating.

FIG. 8 is a side view in section illustrating a solid substrate coatedwith an alternative wear-resistant reinforcing coating.

FIG. 9 is a view in perspective illustrating a modular molded unitconstructed according to the present invention, including a close-upview of an encircled portion of the molded unit.

In describing the preferred embodiment of the invention which isillustrated in the drawings, specific terminology will be resorted tofor the sake of clarity. However, it is not intended that the inventionbe limited to the specific term so selected and it is to be understoodthat each specific term includes all technical equivalents which operatein a similar manner to accomplish a similar purpose. For example, theword connected or term similar thereto are often used. They are notlimited to direct connection, but include connection through otherelements where such connection is recognized as being equivalent bythose skilled in the art.

(h) DETAILED DESCRIPTION OF THE INVENTION

The present invention includes several embodiments, all of which involveadding reinforcing fibers to a liquid matrix material. The liquid matrixmaterial hardens when cured, thereby forming a rigid matrix in whichother material, such as the reinforcing fibers and/or a particulate,such as sand or gravel, are retained to reinforce and add otherdesirable characteristics to the matrix. The coating, once hardened,provides a very strong, highly wear resistant coating.

The components are carefully chosen to produce a final coating that hasa very advantageous combination of features. The liquid matrix materialis preferably a conventional translucent or transparent two-part epoxyresin and hardener that is mixed prior to including the fibers orparticulate. Of course, the liquid matrix material could be dyed to anopaque or translucent color. The liquid matrix material can be anacrylic, polyurethane, polycarbonate or other liquid that forms a rigidpolymer matrix when cured or hardened. Thus, the term “liquid matrixmaterial” includes any liquid that hardens to form a polymer matrix thatadheres to the reinforcing fibers and particulate.

The fibers can be in the form of a mat (woven or non-woven) orindividual fibers, such as short chopped fibers or long intertwinedfibers. The fibers themselves can be made of glass, carbon, synthetic,nylon, or any material that adheres to a cured matrix material.

The wear-resistant reinforcing coating is formed on a substrate. Thesubstrate upon which the coating is formed can be a solid substrate. Theterm “solid substrate” includes any unitary substrate, including bondedparticulate, such as concrete and asphalt pavement, and compositematerials, such as cement board, fiberglass/resin and wood, includingnatural wood and fabricated wood products, such as plywood,particle-board and oriented strand-board. Solid substrates also includemetal and any conventional non-carpet flooring, such as ceramic andmarble tile, linoleum, laminate and hardwood. Interlocking or abuttingdiscrete flooring units, such as bricks, pavers and boards on woodendecks, that are combined to form a contiguous surface of material thatdoes not move or shift readily under traffic are also solid substrates.

The substrate alternatively can be particulate, which is defined as anynon-bonded particles such as soil, sand, gravel or a combination ofthese. Particulate can be compacted or loose, and commonly shifts whentraffic is upon it. Particulate substrates generally absorb liquids.Solid substrates tend to absorb less liquid than particulate substrates,although virtually all solid substrates absorb some liquid.

One method of forming the wear-resistant reinforcing coating on asubstrate of either type is illustrated in FIG. 1. The substrate surfacemust be prepared to receive the wear-resistant reinforcing coating. If,for example, the substrate is a solid substrate, such as the concretesubstrate 10 shown in FIG. 7, it must be in sound condition. Anydeterioration or spalling must be removed, and prior to application theentire surface to be bonded should be roughened to a course sandpapertexture either by sandblasting, shot blasting, water blasting, orgrinding with a scarifier. Solid substrates must next be cleaned of alldirt, dust, debris, grease, laitance, and moisture. After the surface iscleaned, a structural epoxy paste may need to be applied to fill voidsto keep absorption of liquid resin from being too high. Alternatively,or in addition, the solid substrate can be “primed” with epoxy byrolling, spraying or otherwise applying the epoxy in a thin coating overthe substrate.

If the base substrate is particulate, as is the soil, sand and gravelsubstrate 30 of FIG. 2, it should preferably be compacted to ensure thatno significant settling will occur after curing of the resin. Compactionis not necessary, but it is desired in most circumstances. Regardless ofthe substrate type, the surface should be smooth and level, and free ofall ridges and uneven areas. Any ridges and uneven areas can be taperedto an even flat surface by using a trowel and the structural epoxypaste. In some cases when the voids to be filled or evened out are toolarge and deep for paste epoxy alone, dry clean sand can be added to thestructural epoxy paste using, for example, a ratio of 1:1 sand to epoxyto form an epoxy mortar, which can then be used to fill voids and smoothridges.

Once the surface is prepared, the liquid epoxy resin is combined withparticulate in a conventional mortar mixer that is used to mix concrete.The liquid epoxy and the particulate, such as small, colored stones, arerotated and thereby mixed together thoroughly. While the epoxy andstones are mixing, the substrate to be coated with the wear-resistantreinforcing coating is covered with reinforcing fibers. In the preferredembodiment, a fabric mat 12 of woven fibers is placed over the substratesurface, as shown in FIG. 7, with the direction of the fiberstransverse, and preferably perpendicular, to any cracks. If the cracksare oriented in multiple directions, the mat is aligned in the bestorientation to reinforce the cracks, or a nonwoven mat that has fibersoriented in various directions is used.

Once the mat of reinforcing fibers is in place on the substrate, themixture of epoxy resin and stones is poured onto the mat, and themixture is spread by a trowel or other tool over the mat, untilsubstantially all of the mat is wetted by the epoxy resin, the solidsubstrate is wetted by the epoxy resin and the top surface of thecoating has the desired final contour, which is ordinarily flat. Thislayer 14 of resin and particulate is shown in FIG. 7. If the resin isself-curing, the mixture is simply allowed to cure over time, afterwhich it can be used. The cured composite of polymer matrix reinforcingfibers forms a rigid, wear-resistant coating that also reinforces thebase to which it adheres.

If one wishes to accelerate the curing of an epoxy resin, one can heatthe mixture, such as by radiant heaters or warm air. Alternatively,heating wires or tubes, such as the tubes 16 and 18 shown in FIG. 7carrying heated water, can be embedded in the mixture to melt snow andice. These same tubes or wires can be used to heat the resin duringcuring, thereby accelerating the curing time.

As indicated in FIG. 1 and shown in the final product of FIG. 2, apossible additional step is the interposition of a membrane 32 betweenthe substrate 30 and the mixture of resin, fiber mat and stone 34. Thisstep is taken prior to the placement of the fiber mat on the substrate,and has the effect of preventing or limiting absorption of the resininto the substrate, thereby preventing or limiting adhesion of thecoating to the substrate. Limiting adhesion has the advantages ofpermitting removal later, such as for remodeling, without destroying theunderlying substrate. Furthermore, limiting adhesion also permits theunderlying substrate and the coating to move relative to one another,for example due to expansion and contraction due to humidity andtemperature changes. Additionally, if the absorption of the epoxy resininto the substrate is significant, the particulate and fibers can become“starved” of matrix material, thus resulting in a defective finishedcomposite. The interposed membrane also eliminates this problem.

One type of membrane is a release agent, for example oil, wax, grease,etc., that is applied to the substrate in a thin coating like a paint.The release agent forms a thin film that prevents or limits the curedcoating from adhering to the substrate by preventing adhesion to therelease agent. Alternatively, the coating may adhere to the releaseagent if the release agent does not adhere significantly to thesubstrate, as would be the case, for example with wax. Thus, therelease-agent type of membrane has the advantages described above.

A different type of membrane can be placed over the substrate prior toapplication of the fibers, epoxy and particulate. This membrane is aconventional polymer sheet, shown in FIG. 2, which has the sameadvantages described above. The polymer sheet membrane has theadditional advantage that if there are gaps between pieces of thesubstrate, such as on a wooden deck (see FIG. 3) and a brick sidewalk, aconventional polymer sheet membrane will bridge those gaps and supportsthe resin until it cures and becomes rigid. The polymer sheet membranealso prevents substantial draining of the epoxy from the mixture onto anunderlying surface through large gaps.

Once the composite has cured, it acts as a “bridge” across the gapsbetween the wood to support traffic even above the gaps. The fibersembedded in the matrix also help keep the stones or other particulateembedded in the matrix together, which is especially important if thecoating does not adhere to the substrate.

A second method of applying the liquid matrix material, such as epoxyresin, is to apply it to the substrate surface after preparing thesubstrate surface and before combining particulate, such as stones, withthe resin, as illustrated in FIG. 4. The application of the resin can beaccomplished by spraying, or by using a medium to heavy nap roller or bypouring the resin onto the substrate and then spreading with a squeegee.

After the resin is applied liberally, a fiber mat is unrolled over thesubstrate. Alternatively, loose fibers could be applied in addition to,or instead of, the mat. Using a tined roller, pressure is applied to themat to remove any air voids and excess epoxy. After the fibers areworked into the resin another coat of resin is optionally applied andworked into the fibers. The surface should have a heavy enough resincoat on it that none of the fibers can be distinguished through the topsurface of the resin.

Once the fiber mat is all worked into the resin, a layer of particulate,such as sand or small stones, is applied to the top of the resin to formthe wearing course. Particulate can be applied to the mixture bysprinkling, blowing or some other means that forms a layer ofparticulate. Any leveling or spreading of the coating should beperformed while the resin is still in liquid form. Once the coating isleveled, any loose particulate can be blown, swept or otherwise removedfrom the surface and another coat of resin can be added to form a sealedsurface if desired. The total thickness of the wear-resistantreinforcing coating is typically between about one-eighth andthree-quarters of an inch thick. A coating applied according to thismethod to a concrete solid substrate is virtually identical to thecoating shown in FIG. 7.

As an alternative to forming the wear-resistant reinforcing coating onsolid substrates, such as concrete, the present invention can be appliedto particulate substrates, such as sand, soil, gravel or any mixture ofthese materials. Preferably, the substrate surface is prepared bycompacting it to reduce subsequent settling and to reduce excessiveabsorption of the resin. Once the substrate is prepared, the method asdescribed above in relation to FIGS. 1 and 4 can be carried out. Acoating formed on a particulate substrate is shown in the illustrationof FIG. 2. Of course, a membrane can be interposed between a particulatesubstrate and the fibers, resin and particulate coating.

In addition to forming a wear-resistant reinforcing coating oncontiguous solid substrates, a wear-resistant reinforcing coating can beformed on a wood deck that has discontinuities, such as significant gapsbetween the boards thereof. In order to form such a coating, the woodendeck 50 must first be covered by a membrane 52, such as plasticsheeting, as shown in FIG. 3. Alternatively, sheeting, such as cementboard, plywood or oriented-strand board, that slows or stops the flow ofliquid resin through the gaps between the boards can be used between theplastic membrane and the wooden boards, but plastic sheeting ispreferred by itself due to its cost and effectiveness. Any seams aresealed by tape or other adhesive. Once the membrane is in place, one ofthe methods of forming the coating as described above in relation toFIG. 1 or 4 is carried out. The finished coating 54 is shown in FIG. 3applied to the wood deck substrate 50, in which the cured compositeabove the gaps between the wooden boards supports traffic.

The preferred method can be practiced according to yet anotherembodiment. Prior to applying ceramic or marble tile to a woodsub-floor, it is common to rigidify the sub-floor with a second layer ofplywood, oriented strand board (OSB) or other sheeting product. However,in an alternative embodiment of the present invention, the sub-floor 80is reinforced with a composite and then topped with a flooring material,such as tile.

The first step in this alternative process, illustrated in the diagramof FIG. 5, is to prepare the sub-floor substrate 80, shown in FIG. 8,for adhesion of the liquid matrix material, such as by cleaning and, ifnecessary, sanding to permit sufficient absorption. Next, reinforcingfibers, loose or in a mat 82, are then spread over the sub-floor, andthen the liquid matrix material, such as liquid epoxy resin, is applied,such as by pouring, spraying, etc., onto the floor and the fibers. Theresin wets the fibers and absorbs into the sub-floor to adhere to boththe fibers and the sub-floor and form a composite coating upon curing.The resin is then hardened as described above. After the liquid matrixmaterial cures, the composite reinforced floor is not suitable fortraffic, because it has a slippery top surface that also does not wearwell. Tile, such as ceramic tile 84, is adhered to the cured compositeto provide a wearing surface that is suitable for traffic. Because thesub-floor is substantially reinforced by the composite, neither thetile, nor its grout, will crack due to flexing of the underlyingsub-floor. The wear-resistant reinforcing coating, comprising the resinmatrix with embedded reinforcing fibers 82 and the flooring, such astile 84, have advantages not heretofore seen.

Some kinds of tile adhesives may not adhere to some kinds of matrixmaterials. Therefore, particulate, such as sand, can be sprinkled uponthe epoxy prior to curing. This will prevent slipping before the tile islaid, and will promote adhesion between the matrix and the subsequentlyapplied tile adhesive.

Another embodiment of the present invention relates to the formation ofdiscrete modular molded units, such as stepping stones, bricks andsimilar structures. These molded units are made by constructing theabove-described composites within the confines of one or more molds,such as a round pan. In an exemplary process illustrated in the diagramof FIG. 6, fibers 100 are placed in the mold. A finished molded unit isshown in FIG. 9. A liquid matrix material, such as epoxy resin, is mixedwith stones and the mixture is poured into the mold over the fibers. Theliquid matrix material wets the fibers and causes them to becomeembedded within it. After the resin wets the fibers, the liquid matrixmaterial is hardened, thereby forming a rigid matrix reinforced byfibers that is subsequently removed from the mold. The top, wearingsurface of the molded unit is formed by the stones coated with epoxyresin 102, which adheres the stones to the fibers. Alternatively, aswith the embodiments for coating existing substrates, rather thancombining the resin and particulate prior to applying to the fibers, theparticulate can be placed on the resin after the resin has been pouredonto the fibers.

Still another alternative embodiment includes the use of an alreadycured composite adhered to the substrate. For example, a compositeplate, which is a rigid polymer matrix embedded with reinforcing fibers,is adhered to a substrate using an epoxy resin applied either to thesubstrate or to the plate, or both. The plate is pressed against thesubstrate with the epoxy resin interposed between the substrate and theplate. Another layer of resin is then applied to the exposed majorsurface of the plate and particulate is applied thereto. Alternatively,particulate and resin can be combined prior to depositing on thecomposite plate, and then poured and spread over the composite plate.Once the resin is hardened, a wear-resistant reinforcing coating isformed on the substrate.

Many embodiments of the present invention have been illustrated anddescribed. There are many substrates, membranes, resins and particulatesshown and described in several combinations. Of course, it is possibleto make other combinations not shown, including combining any solidsubstrate with or without a membrane or release agent between thesubstrate and the liquid matrix material. Furthermore, any particulatesubstrate can be combined with or without a membrane or release agentbetween the substrate and the liquid matrix material. Such othercombinations will become apparent to those of ordinary skill from theabove description.

While certain preferred embodiments of the present invention have beendisclosed in detail, it is to be understood that various modificationsmay be adopted without departing from the spirit of the invention orscope of the following claims.

1. A method of forming a wear-resistant reinforcing coating on aparticulate substrate, the method comprising: (a) disposing reinforcingfibers on the particulate substrate; (b) applying a liquid matrixmaterial to the reinforcing fibers; (c) placing particulate in contactwith the liquid matrix material on an opposite side of the liquid matrixmaterial from the particulate substrate; and (d) hardening the liquidmatrix material, thereby forming a composite of reinforcing fibers in amatrix of the hardened liquid matrix material with the wear resistentsurface of particulate.
 2. The method in accordance with claim 1,wherein the particulate substrate is soil.
 3. The method in accordancewith claim 1, wherein the particulate substrate is sand.
 4. The methodin accordance with claim 1, wherein the particulate substrate is gravel.5. The method in accordance with claim 1, wherein the particulatesubstrate is a combination selected from the group of soil, sand andgravel.